Cause and Effect Chart

Cause and Effect Analysis is a technique that helps you identify all the likely causes of a problem. The diagrams you create with this type of analysis are sometimes known as fishbone diagrams because they look like the skeleton of a fish.

This technique was developed by Professor Ishikawa in the 1960s and there are four characteristics of the Cause and Effect Principle

• Write down the problem
• Work out the major factors involved
• Identify possible causes         
• Analyze your diagram

Step 1 – Write down the Problem

Having defined and identified the problem, now we need to chart all the relevant information.

• Work with a large sheet of paper.
• On the right-hand side of the paper draw a box
• Write the problem name in the box
• Draw a horizontal line across the paper from the box

This arrangement, which will look like the head and spine of a fish, gives you space to develop ideas.

We are going to work through each process using a fictitious example of an organization that has identified an ongoing problem with bearings.

One box with the statement ‘Bearing Failures’

One horizontal line across the page

Step 2 – Work out the Major Factors Involved

Now we need to identify the factors that may be part of the problem. These may be systems, equipment, materials, external forces, people involved with the problem, and so on. We need to try to draw out as many of these as possible and brainstorm any other factors that may affect the situation, then draw a line off the “spine” of the diagram for each factor, and label each line.

A Root Cause Analysis initiative is implemented and the following factors are identified and added to the diagram – Design, Fitting, Maintenance, and Operations

Draw lines up and down as shown and mark as Design, Fitting, Maintenance, and Operations

Step 3 – Identify Possible Causes

For each of the factors you considered in step 2, now brainstorm possible causes of the problem that may be related to the factor. Show these possible causes as shorter lines come off the “bones” of the diagram. Where a cause is large or complex, then it may be best to break it down into sub-causes. Show these as lines coming off each cause line.

A brainstorming session should be arranged to identify possible causes for each of the factors identified in step 2 which are added to the diagram

Draw short horizontal lines as shown  and mark with potential identified causes

Step 4 – Analyse Your Diagram

By this stage, you should have a diagram showing all the possible causes of the problem that you can think of. Depending on the complexity and importance of the problem, you can now investigate the most likely causes further, which may involve the setting up of investigations, carrying out surveys, and whatever else may be deemed viable and important. These will be designed to test which of these possible causes are actually contributing to the problem.

The analysis has now been completed.

Without this analysis, assumptions would have been made regarding causes and perhaps quick-fix tasks undertaken without having identified the root cause of the problem. The best approach now is to take each of the identified causes and start to investigate potential effective solutions.

Cause and Effect Chart – Additional Guidelines

A useful way to use this technique with a team is to write all of the possible causes of the problem down on sticky notes. You can then group similar ones together on the diagram.

This approach is sometimes called CEDAC (Cause and Effect Diagram with Additional Cards) and was developed by Dr. Ryuji Fukuda, a Japanese expert on continuous improvement.

When creating the chart, use post it’s and technology where relevant (Computer and projector). It is not an exact science. There is no 100% correct Cause and Effect Chart.

Keep it simple

• Only one cause per box
• Use nonverb statements for causes
• It is easier to edit than it is to create

Let’s move on to our search to find ‘Effective Solutions’.

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